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United States Patent |
5,009,079
|
Zinsmeyer
|
April 23, 1991
|
Refrigerant flow control device
Abstract
A simple flow control device is provided in a condensate drain pipe to
prevent the flow of refrigerant vapor therethrough and to regulate the
flow of liquid refrigerant as a function of the level of accumulated
liquid refrigerant in the drain pipe. The only moving part is a float
device that rides up on a cylindrical valve body in response to the level
of liquid refrigerant to thereby expose slots in the valve body which
allow for the flow of liquid refrigerant to the refrigerant return line to
the cooler.
Inventors:
|
Zinsmeyer; Thomas M. (Pennellville, NY)
|
Assignee:
|
Carrier Corporation (Syracuse, NY)
|
Appl. No.:
|
457228 |
Filed:
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December 26, 1989 |
Current U.S. Class: |
62/218; 137/192; 137/399 |
Intern'l Class: |
F25B 041/04 |
Field of Search: |
137/192,399,432
62/218
|
References Cited
U.S. Patent Documents
47304 | Apr., 1865 | Hogg | 137/192.
|
130490 | Aug., 1872 | Dick | 137/192.
|
921865 | May., 1909 | Miller et al. | 137/192.
|
1766966 | Jun., 1930 | Walsh | 137/192.
|
2299360 | Oct., 1942 | Tharp | 137/432.
|
2613922 | Oct., 1952 | Gatchet | 137/192.
|
3399544 | Sep., 1968 | Osborne | 62/218.
|
Foreign Patent Documents |
73678 | ., 1894 | DE | 137/192.
|
Primary Examiner: Tapolcai; William E.
Claims
What is claimed is:
1. An improved refrigerant flow control device of the type having a float
which is responsive to the liquid level of refrigerant in a condenser sump
to control the flow of refrigerant from the sump comprising:
a standpipe extending upwardly from a lower portion of the sump, said
standpipe having its upper end closed and having near its lower end at
least one opening formed to provide fluid communication from the lower
portion of the sump to a refrigerant return line below; and
a float device slideably disposed on said standpipe in such a way that when
the liquid level of refrigerant in the sump is below a predetermined
level, said float device is caused to rest at a vertical height on said
standpipe such that it covers said at least one opening, and when the
liquid level of refrigerant rises above said predetermined level, said
float device is caused to slide upwardly to uncover said at least one
opening and allow liquid refrigerant to flow from the sump; wherein said
float device has an undercut portion surrounding said standpipe such that
the amount of surface contact between said float device and said standpipe
is reduced.
2. An improved refrigerant flow control device as set forth in claim 1
wherein said standpipe is of a cylindrical shape.
3. An improved refrigerant flow control device as set forth in claim 1
wherein said at least one opening comprises an elongate slot formed in the
side of said standpipe.
4. An improved refrigerant flow control device as set forth in claim 1
wherein said at least one opening comprises a plurality of openings
symmetrically located on the sides of said standpipe.
5. An improved refrigerant flow control device as set forth in claim 1
wherein said float device is generally toroidally shaped with a
cylindrical cavity at its center.
6. An improved refrigerant flow control device a set forth in claim 1
wherein said flow device includes a cylindrical sleeve with a beveled
portion at one end thereof to reduce the surface contact between said
sleeve and a portion of a said standpipe on which it rests.
7. An improved refrigerant flow control device as set forth in claim 1
wherein said float device undercut portion is so disposed that said float
device engages said standpipe only at top and bottom portions of said
float device.
8. An improved refrigerant flow control device of the type having a float
which rises with the level of liquid refrigerant in the sump of a
condenser to control the flow of refrigerant from a discharge opening in
the bottom of the sump comprising:
a standpipe extending upwardly from the discharge opening and having at
least one side opening in a lower portion thereof, said side opening
fluidly communicating with said discharge opening, and
a float element mounted on said standpipe and vertically movable thereon
between a lower position wherein said float element covers said side
discharge opening to prevent the flow of refrigerant therethrough and
increasingly higher positions wherein said flow element uncovers
increasingly greater portions of said opening to allow increasingly
greater flow of refrigerant therethrough, wherein said float element has
an undercut portion surrounding said standpipe such that the amount of
surface contact between said float element and said standpipe is reduced.
9. An improved refrigerant flow control device as set forth in claim 8
wherein said standpipe is cylindrical in form.
10. An improved refrigerant flow control device as set forth in claim 8
wherein said at least one side opening comprises a vertical slot formed in
the side of said standpipe.
11. An improved refrigerant flow control device as set forth in claim 9
wherein said float element is generally toroidal in form.
12. An improved refrigerant flow control device as set forth in claim 8
wherein said float element is composed of a slurry of microballs
adhesively held together by epoxy.
13. An improved refrigerant flow control device as set forth in claim 8
wherein said refrigerant comprises R-22.
Description
BACKGROUND OF THE INVENTION
This invention relates generally to refrigeration systems and, more
particularly, to a device for controlling the flow of refrigerant from the
high to the low side of the system.
In a centrifugal chiller refrigeration system, liquid refrigerant flows to
a lower sump portion of a condenser from which it then must be metered to
a cooler as part of the refrigeration cycle. A common approach for
accomplishing this metering function has been with the use of a float bulb
connected to a guillotine valve. Such an apparatus allows the refrigerant
flow to be responsive to the level of liquid refrigerant in the sump and
also provides a liquid seal to prevent the flow of gaseous refrigerant to
the cooler. Typical of such devices are those shown in U.S. Pat. Nos.
3,365,899 and 3,399,544 assigned to the assignee of the present invention.
Although these devices are effective in operation, they are relatively
complicated and expensive because of the close tolerances that are
required. For the same reason, their reliability is also sometimes less
than desired.
Because of the above-mentioned complications, a more prevalent approach in
the industry has been the use of a simple fixed orifice to accomplish the
metering function. With no moving parts, this design is simple, reliable
and effective for the purpose intended. Since the orifice must be sized
for a 100 percent load, it is relatively large in size. If the system is
operating at part load, then the large sized orifice allows not only
liquid refrigerant to pass, but also the gaseous refrigerant. Although
this refrigerant gas flow represents a parasitic loss in the system, it
has heretofore been tolerated for the sake of simplicity and reliability.
Heretofore the preferred refrigerant for centrifugal chiller refrigeration
applications has been R-11. But, because of possible detriment to the
environment, there is a movement in the refrigeration industry to use
alternative refrigerants in such systems. One of these alternatives is
R-22, which operates at higher pressures and is therefore a much more
dense refrigerant (i.e. by a factor of 8) and one which provides a
substantially reduced refrigeration cycle efficiency. The use of the
higher density refrigerant thus becomes significant in a number of aspects
with regard to the gas bypass that has been tolerated as discussed
hereinabove. Because of the reduced cycle efficiency, the parasitic losses
become more critical. Secondly, because the refrigerant is substantially
more dense, a given volume of gaseous refrigerant that is bypassed
represents a proportionately greater loss. Finally, because of the
inherent need for a high pressure machine (i.e. 300 PSI versus 15 PSI), a
given volume loss represents, again, a greater proportionate loss than
with a low pressure system. For these reasons, the parasitic losses that
have heretofore been tolerated are no longer acceptable. But, on the other
hand, it is not desirable to return to the relatively complicated types of
float bulb valves that were previously used.
It is therefore an object of the present invention to provide an improved
refrigerant flow metering apparatus for a centrifugal chiller system.
Another object of the present invention is the provision for a refrigerant
flow control device which operates to prevent the bypassing of refrigerant
gas.
Yet another object of the present invention is the provision in a
centrifugal chiller system for a refrigerant flow control device which is
simple and reliable in construction.
Yet another object of the present invention is the provision in a
centrifugal chiller system for a refrigerant flow control apparatus which
is economical to manufacture and simple and effective in use.
These objects and other features and advantages become more readily
apparent upon reference to the following description when taken in
conjunction with the appended drawings.
SUMMARY OF THE INVENTION
Briefly, in accordance with one aspect of the invention, a standpipe
extends upwardly from a lower portion of the condenser sump and a
plurality of openings are symmetrically provided on the sides of the
standpipe, near the lower end thereof. A float is slideably disposed over
the standpipe so as to cover the openings when the liquid level of the
refrigerant is below a predetermined level, and when the refrigerant rises
above a predetermined level, the float is caused to rise so as to uncover
the openings and allow liquid refrigerant to flow therethrough to a cooler
below. In this way, the refrigerant flow control is simply and effectively
made responsive to the level of liquid refrigerant in the sump while, at
the same time, preventing any bypass of refrigerant gas through the
openings.
By another aspect of the invention, the float device is so shaped at the
surface which interfaces with the standpipe that the float is prevented
from hanging up in a fixed position on the standpipe because of frictional
resistance. More specifically, the float element is undercut along most of
its length such that it contacts the standpipe only at the top and bottom
portions thereof.
By yet another aspect of the invention, the bottom portion of the float is
so shaped as to prevent the float from sticking to a portion of the
standpipe. The float includes a cylindrical sleeve with the bottom portion
beveled in order to reduce the surface contact with that portion of the
standpipe on which it rests.
In the drawings as hereinafter described, a preferred embodiment is
depicted; however, various other modifications and alternate constructions
can be made thereto without departing from the true spirit and scope of
the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a partial front view of a condenser with the flow control
apparatus of the present invention incorporated therein.
FIG. 2 is a bottom view of the flow control apparatus portion of the
invention.
FIG. 3 is an exploded view of the flow control apparatus portion of the
invention.
FIG. 4 is a sectional view of the float device portion of the invention.
Referring now to FIGS. 1 and 2, the invention is shown generally at 10 as
installed in the condensate drain pipe 11 of a condenser 12 having a
plurality of tubes 13 mounted therein for purposes of cooling the
refrigerant and causing it to flow to the bottom of the condenser 12 and
out the condensate drain pipe 11, from which it then flows to a cooler
(not shown) by way of the flow control apparatus to be described herein.
The condensate drain pipe 11 extends downwardly from the lower portion of
the condenser 12 and has attached to the periphery of its lower end, by
welding or the like, a mounting flange 14. Attached to the mounting flange
14 is an access plate 16, which is removably secured to the mounting
flange 14 by a plurality of bolts 17 and nuts 18. The flow control device
of the present invention is attached to the top side 19 of the access
plate in a manner to be described hereinafter, and operates to control the
flow of liquid refrigerant passing through the condensate drain pipe 11
and through a central opening 21 of the access plate 16, where it is then
discharged to a refrigerant return line 22. The refrigerant return line 22
is fluidly connected to the central opening 21 by way of a mounting flange
23 and a plurality of bolts 24, as shown in FIG. 2. Its other end is
fluidly connected to the evaporator, or cooler, in a conventional manner.
Referring now to FIG. 3, the flow control device is shown to include a base
26, a valve body 27, and a float device 28. These elements are shown in
the assembled positions in FIG. 1 with the base 26 being attached to the
access plate top side 19 by fasteners 29, with its cylindrical central
opening 31 coinciding with that 21 of the access plate 16. This base
structure 26 simply provides a means of mounting the valve body 27 to the
access plate 16. The valve body 27 includes a lower cylindrical section
31, an upper cylindrical 32, and an intermediate flange 33. In its
installed position, the lower cylindrical section 31 is slideably disposed
in the base central opening 30, with the intermediate flange 33 resting on
the top surface of the cylindrical upper portion 34 of the base 26 as
shown in FIG. 1.
Formed in the upper cylindrical section 32 of the valve body 27 are a
plurality of circumferentially spaced, elongate slots 36, whose axial
positions and lengths are predetermined so as to bring about the desired
performance characteristics when the float device device 28 operates with
conjunction therewith.
Referring to FIG. 4, the float device 28 comprises a cylindrical sleeve 37
with a toroidal shaped collar 38 fixedly mounted to its periphery. The
sleeve 37 has upper and lower contact surfaces 39 and 41, which are of a
reduced, and closely controlled, diameter, such that when the sleeve 37 is
slideably mounted on the valve body upper cylindrical 32, there is little
friction between the mating elements. Between the upper and lower contact
surfaces 39 and 41, there is a clearance space 42 which ensures that
frictional contact is not established between the upper and lower contact
surfaces 39 and 41. Further, a beveled portion 43 is provided at the upper
end of the sleeve 37 in order to further prevent the hanging up of the
sleeve 37 as it freely slides on the valve body upper cylindrical section
32. The sleeve 37 is preferably made of the same material as the valve
body 27. A material that has been found to be suitable is a half hard,
XB40-8 (copper alloy C36000).
Rigidly secured to the outer periphery of the sleeve 37 is the collar 38
which is made of a flotation material that is resistant to chemical
reaction with the refrigerant. A material that has been found to be
suitable for this purpose is a syntactic foam composed of a slurry of
micro balls adhesively held together by epoxy, with a density of 21-25
lbs/ft.sup.3. The collar 38 is preferably molded to the outer periphery of
the sleeve 37 with a peripheral indent 44 being provided on the sleeve 37
in order to prevent any axial relative movement between the two elements.
The height of the collar 38 is slightly less than that of the sleeve 37,
such that the sleeve extends downwardly further than the collar 38. The
outer side of the sleeve 37 is beveled at 46 in order to reduce the
contact surface area between the sleeve 37 and the top of the intermediate
sleeve 33 on the valve body 27.
The float device 28 is designed to slideably move between the closed
position where the sleeve 37 rests on the valve body intermediate portion
33 and between the open position where the sleeve 37 moves to the top of
the valve body cylindrical section 32 as shown in FIG. 1. A stop plate 47
is secured by way of fastener 48 to the top end of the valve body upper
cylindrical section 32 so as to limit the upward movement of the flow
device 28 to that shown in FIG. 1. Recognizing that solid particles may
tend to be immersed in the refrigerant passing through the condensate
drain pipe 11, a protective screen 49 is provided to surround and protect
the flow control device. The protective screen device 49 comprises a
cylindrical screen portion 51 secured between solid end portions 52 and
53, which are formed of a suitable material such as sheet metal. The
protective screen 49 is mounted to the access plate top side 19 by a
plurality of bolts 54.
In operation, the flow control device functions as follows. When the level
of the liquid refrigerant in the condensate drain pipe 11 is no higher
than the bottom of the slots 36, the float device 28 will remain in the
fully closed (i.e., the lowermost position as shown in FIG. 1), and
neither liquid refrigerant nor refrigerant vapor will be allowed to pass
to the refrigerant return line 22. As the level of the liquid refrigerant
increases to the point that it is above the lower portion of the slots 36,
it will then be in contact with the lower surface of the collar 38. When
the upward force of the buoyancy is sufficient to overcome the weight of
the float device 28, it will rise to uncover the slots 36 so that liquid
refrigerant can pass through the slots 36, through the openings 30 and 21
and finally to the refrigerant return line 22. It will be recognized,
however, that the level of liquid refrigerant in the condensate drain pipe
11 will always be above the level of the exposed slots when the valve is
open, such that refrigerant vapor will be prevented from entering the
slots 36. In this way, only liquid refrigerant will pass to the condensate
drain pipe, and the volume of flow will be automatically regulated in
response to the level of liquid refrigerant in the condensate drain pipe
11.
While the present invention has been disclosed with particular reference to
a preferred embodiment, the concepts of this invention are readily
adaptable to other embodiments, and those skilled in the art may vary the
structure thereof without departing from the essential spirit of the
present invention.
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